OBJECTIVES: 1. Modified Histones in HeLa and friend Erythroleukemia Cells Treated with n-Butyrate. 2. Stimulation of Heme Accumulation and Erythroid Colony Formation in Cultures of Chick Bone Marrow Cells by Chick Plasma. 3. Chromatin Changes and DNA Synthesis in Friend Erythroleukemia and HeLa Cells during Treatment with DMSO and n-Butyrate.